Pixels values are packed as 16-bit UNORM values, so the matrix offset
components must be multiplied properly by the idempotent element -i.e.
number 1 encoded as 16-bit UNORM-.
Signed-off-by: Ariel D'Alessandro <ariel.dalessandro@collabora.com>
---
drivers/gpu/drm/vkms/vkms_composer.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/vkms/vkms_composer.c b/drivers/gpu/drm/vkms/vkms_composer.c
index cd85de4ffd03d..d53ea4189c97b 100644
--- a/drivers/gpu/drm/vkms/vkms_composer.c
+++ b/drivers/gpu/drm/vkms/vkms_composer.c
@@ -17,6 +17,8 @@
#include "vkms_composer.h"
#include "vkms_luts.h"
+#define UNORM_16BIT_ONE (1ULL << 16)
+
static u16 pre_mul_blend_channel(u16 src, u16 dst, u16 alpha)
{
u32 new_color;
@@ -139,20 +141,25 @@ VISIBLE_IF_KUNIT void apply_3x4_matrix(struct pixel_argb_s32 *pixel,
g = drm_int2fixp(pixel->g);
b = drm_int2fixp(pixel->b);
+ /*
+ * Pixels values are packed as 16-bit UNORM values, so the matrix offset
+ * components must be multiplied properly by the idempotent element -i.e.
+ * number 1 encoded as 16-bit UNORM-.
+ */
rf = drm_fixp_mul(drm_sm2fixp(matrix->matrix[0]), r) +
drm_fixp_mul(drm_sm2fixp(matrix->matrix[1]), g) +
drm_fixp_mul(drm_sm2fixp(matrix->matrix[2]), b) +
- drm_sm2fixp(matrix->matrix[3]);
+ drm_fixp_mul(drm_sm2fixp(matrix->matrix[3]), drm_int2fixp(UNORM_16BIT_ONE));
gf = drm_fixp_mul(drm_sm2fixp(matrix->matrix[4]), r) +
drm_fixp_mul(drm_sm2fixp(matrix->matrix[5]), g) +
drm_fixp_mul(drm_sm2fixp(matrix->matrix[6]), b) +
- drm_sm2fixp(matrix->matrix[7]);
+ drm_fixp_mul(drm_sm2fixp(matrix->matrix[7]), drm_int2fixp(UNORM_16BIT_ONE));
bf = drm_fixp_mul(drm_sm2fixp(matrix->matrix[8]), r) +
drm_fixp_mul(drm_sm2fixp(matrix->matrix[9]), g) +
drm_fixp_mul(drm_sm2fixp(matrix->matrix[10]), b) +
- drm_sm2fixp(matrix->matrix[11]);
+ drm_fixp_mul(drm_sm2fixp(matrix->matrix[11]), drm_int2fixp(UNORM_16BIT_ONE));
pixel->r = drm_fixp2int_round(rf);
pixel->g = drm_fixp2int_round(gf);
--
2.51.0